Recently, augmented reality (AR) is gaining increasing attention for use in mobile phones, and hand gesture recognition (HGR) is considered as an important interaction technique in the mobile AR applications. By using HGR technology, users can directly see the interaction with the virtual image in the mobile phone's display. The mainstream technologies for HGR are based on 3-D cameras such as Microsoft Kinect, Intel RealSense and Leap Motion. In a 3-D camera, RGB and infrared (IR) cameras are used to produce images and their depth information, respectively, for HGR. However, the mobile phone equipped with an extra IR camera has the disadvantages of extra cost and greater power/resource consumption. Additionally, the IR cameras function poorly outdoors or in bright light. These disadvantages of IR cameras restrict the evolution of HGR in mobile phones.